Depth illusion attachment device for optical projectors



May 25, 1954 1.. GOULD DEPTH ILLUSION ATTACHMENT DEVICE FOR OPTICAL PROJECTORS Filed Aug. 50, 1949 T I IgENTOi. BY 485g; Od/

HTTYS Patented May 25, 1954 DEPTH ELLUSION ATTACHMENT BEVICE FOILOBTICAL PROJECTORS Leigh Gould, Detroit, .Mich.

ApplicationAugust 30, 1949; Serial'No. 113,174

1 Claim.

This invention, relates to optical projectors and, in particular, to attachments for such projectors;

One object of this invention is to provide a device for use, with the projection lens of an optical projector, such as for motion picture film, which will give the observer a three-dimensional impression of depth.

Another object is to provide a device for use with the projection lens of an optical projector consisting of closely spaced parallel elongated opaque objects such as wires, which when placed in front of the projection lens system alters the appearance of the image seen on the screen and gives to the observer the effect of causing the image to move forward from the screen.

Another object is to provide a device for use with the projection lens of an optical projector, as set forth in the preceding object, wherein the dark portions of the image appear to be separated and brought forward from the light portionsof the.image-,. thereby giving a. threedimensional impression of depth to the observer.

In the drawings:

Figure l is a front elevation, partly in section, of a device for use with the projection lens of an optical projector, according to a preferred form of the invention;

Figure 2 is a horizontal section along the line 22 in Figure 1;

Figure 3 is a vertical section along the line 3-4-3 in Figure 1;

Figure 4 is an enlarged fragmentary front elevation of a modified device for the same purpose;

Figure 5 is a vertical section along the line 5-5 n Figure 4;

Figure 6 is a view similar to Figure 5, but showing a further modification; and

Figure '7 is a diagrammatic view of an optical motion-picture projector showing the device of the present invention attached to the projection lens and viewed in vertical section.

Referring to the drawings in detail, Figures 1 to 3 and 7 show a device generally designated it, which is adapted to be attached to the barrel ll of the projection lens system l2 of an optical projector, generally designated E3. The latter is conventional and any type of projector may be used. The projector shown consists of a lamp house H supported on a pedestal I5 connected to a base (not shown). The lamp house 13 contains a socket 16 in which is mounted a projection lamp bulb H which is wired to the usual source of electric current, such as a house lighting line. Arms l8 and 19 lead upward; and

downward from the lamp house 13 and, support shafts 2e and El upon which are mountedjthe.

film, spools 22 and 23 which accommodate the motion-picture film Mbeing projected.

The motion picture film 24 is fed by means, of sprocket wheels 25 and 28 on shafts 21 and;

to guides 23 and 30 in front of the condensing lens 3i, and in line with the axis of the projection lens system 12. intermittent feed mechanism (not shown), such as an intermittently operated claw or pawl, feeds the film past the guides 29 and St or film gate in a rapidly intermittent manner. shafts iii and it and usually the spool shaft 2! are driven in order to properly feed the film to and from the intermittent feed mechanism. Guide rollers 32 are positioned adjacent the sprockets 2S and it to further guide the film 2e and to assist in forming the proper loops on opposite sides or" the film gates or guides 29 and The usual reflector 33 is mounted behind the projection lamp bulb ii to direct rays into the condenser 3i and thence through the film it to the projection lens system [2.

The device if; of the present invention consists of a tubular barrel 3'3 having an inner bore 35 of substantially the same diameter as the outer diameter of the lens barrel H so as to slip smoothly thereon and be frictionally held. The forward end of the barrel 34 is flanged as at 36 and behind the flange 35 is a reduced diameter bore 31. Behind the bore 31 is a threaded portion 38 which receives a correspondingly threaded retaining ring 39. Mounted between the retaining ring 39 and the flange 38 and held in place thereby is a mounting ring 40. Embedded in the mounting ring til is an alternately opaque and transparent screen 41 consisting of a large number of small diameter opaque rods or wires 42 separated from one another by mi nute spaces 43.

The screen M, for example, may include wires of approximately & of an inch in diameter and spaced apart from one another by intervals of A of an inch. In general, the arrangement of 32 wires per inch is found to be satisfactory. The wires 4| are preferably molded in position at the time the ring it is formed, but may also be inserted in suitable aligned holes 44.

The modified alternately opaque and transparent screen 45 shown in Figures 4 and 5 is similar in purpose to the screen 4| shown in Figures 1 to 3 inclusive and is similarly mounted. The screen however, is formed by providing A conventional The sprocket,

3 parallel grooves 46 of approximately rectangular cross-section in a transparent plate or disc 41 of glass, transparent plastic or the like. These grooves 46 are of the same order of width and spacing as the wires 42 and spaces 43 of Figures 1 to 3 inclusive, but are formed by filling the grooves with opaque material to form opaque hands 48 corresponding to the opaque wires 42. The disc 47 is, of course, mounted in the portion 21 of the barrel 34 in place of the mounting ring The modified alternately opaque and transparent screen 50 shown in Figure 6 is generally similar to that shown in Figures 4 and 5 except that the grooves 5| in the transparent plate or disc 52 are of approximately semi-circular cross-section. The grooves 5| are filled with opaque material to form bands 53 in the same manner and with similar width and separations as the bands 48 in Figure 5. The modified screen 50 is also similarly mounted in the portion 3'! of the barrel 34 in place of the mounting ring 40, and held in position by the retaining ring 39.

In the operation of the invention, the device [0, either with the screen 4! of Figures 1 to 3 inclusive, or the screens 45 or 50 of Figures 4 to 6, is slipped over the lens barrel H. The projection lens 12 is then focussed on the rojection screen and the projector is operated in the usual manner. The device 10, however, gives the eiiect to the observer, of making the image move forward from the screen. In particular, the device seems to separate the light-colored portions from the dark-colored portions of the image and brings the dark-colored portions forward from the lightcolored portions. In this manner, the device gives the observer a three-dimensional impression oi depth to the image which he sees upon the screen. The effect is apparently due to a difiraction phenomenon.

What I claim is:

In combination in an optical film-projection arrangement, a projection screen adapted to receive a greatly-magnified projected image, a film projector disposed remote from said screen, said film projector having a light source, a film holder for the film of which an image is to be projected onto said projection screen, and a projection lens system disposed on the opposite side of said film holder from said light source for projecting said image onto said screen; and a line screen device disposed closely adjacent said projection lens system on the screen side thereof, said device comprising a support having an aperture aligned with said projection lens system and a multiplicity of minutely-spaced elongated opaque parallel bands of substantially equal widths disposed in laterally-spaced relationship across said aperture in a plane substantially perpendicular to the optical axi of said projection lens system, the widths of said bands being approximately one sixtyfourth of an inch and the axial thicknesses of said bands not substantially exceeding their widths.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 817,569 Ives Apr. 10, 1906 1,003,064 Phillips Sept. 12, 1911 1,154,232 Byron Sept. 21, 1915 1,271,667 Coleman July 9, 1918 1,370,885 Frederick et al Mar. 8, 1921 1,438,013 Benson Dec. 5, 1922 1,627,892 Frederick May 10, 1927 1,787,808 Wittel Jan. 6, 1931 1,833,634 Brosse Nov. 24,1931 1,848,253 Howell Mar. 8, 1932 2,029,300 Arfsten Feb. 4, 1936 FOREIGN PATENTS Number Country Date 4,480 Great Britain of 1912 

